1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
18 ////////////////////////////////////////////////////////////////////////////
20 // Transition Radiation Detector version 1 -- slow simulator //
22 ////////////////////////////////////////////////////////////////////////////
27 #include <TLorentzVector.h>
31 #include <TVirtualMC.h>
32 #include <TGeoManager.h>
39 #include "AliTRDgeometry.h"
40 #include "AliTRDhit.h"
41 #include "AliTRDsim.h"
46 //_____________________________________________________________________________
51 ,fTypeOfStepManager(0)
59 // Default constructor
64 //_____________________________________________________________________________
65 AliTRDv1::AliTRDv1(const char *name, const char *title)
69 ,fTypeOfStepManager(2)
77 // Standard constructor for Transition Radiation Detector version 1
80 SetBufferSize(128000);
84 //_____________________________________________________________________________
85 AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
89 ,fTypeOfStepManager(trd.fTypeOfStepManager)
90 ,fStepSize(trd.fStepSize)
93 ,fTrackLength0(trd.fTrackLength0)
94 ,fPrimaryTrackPid(trd.fPrimaryTrackPid)
100 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
101 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
102 fTR->Copy(*((AliTRDv1 &) trd).fTR);
106 //_____________________________________________________________________________
107 AliTRDv1::~AliTRDv1()
110 // AliTRDv1 destructor
130 //_____________________________________________________________________________
131 AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
134 // Assignment operator
137 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
143 //_____________________________________________________________________________
144 void AliTRDv1::Copy(TObject &trd) const
150 ((AliTRDv1 &) trd).fTypeOfStepManager = fTypeOfStepManager;
151 ((AliTRDv1 &) trd).fStepSize = fStepSize;
152 ((AliTRDv1 &) trd).fTRon = fTRon;
153 ((AliTRDv1 &) trd).fTrackLength0 = fTrackLength0;
154 ((AliTRDv1 &) trd).fPrimaryTrackPid = fPrimaryTrackPid;
156 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
157 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
158 fTR->Copy(*((AliTRDv1 &) trd).fTR);
162 //_____________________________________________________________________________
163 void AliTRDv1::AddAlignableVolumes() const
166 // Create entries for alignable volumes associating the symbolic volume
167 // name with the corresponding volume path. Needs to be syncronized with
168 // eventual changes in the geometry.
174 TString vpStr = "ALIC_1/B077_1/BSEGMO";
175 TString vpApp1 = "_1/BTRD";
176 TString vpApp2 = "_1";
177 TString vpApp3 = "/UTR1_1/UTS1_1/UTI1_1/UT";
179 TString snStr = "TRD/sm";
180 TString snApp1 = "/st";
181 TString snApp2 = "/pl";
185 // The symbolic names are: TRD/sm00
189 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
198 symName += Form("%02d",isect);
200 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
205 // The readout chambers
206 // The symbolic names are: TRD/sm00/st0/pl0
210 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
211 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
212 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
214 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
222 volPath += Form("%02d",idet);
226 symName += Form("%02d",isect);
232 printf("volPath=%s\n",volPath.Data());
233 printf("symName=%s\n",symName.Data());
235 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
243 //_____________________________________________________________________________
244 void AliTRDv1::CreateGeometry()
247 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
248 // This version covers the full azimuth.
251 // Check that FRAME is there otherwise we have no place where to put the TRD
252 AliModule* frame = gAlice->GetModule("FRAME");
254 AliError("TRD needs FRAME to be present\n");
258 // Define the chambers
259 AliTRD::CreateGeometry();
263 //_____________________________________________________________________________
264 void AliTRDv1::CreateMaterials()
267 // Create materials for the Transition Radiation Detector version 1
270 AliTRD::CreateMaterials();
274 //_____________________________________________________________________________
275 void AliTRDv1::CreateTRhit(Int_t det)
278 // Creates an electron cluster from a TR photon.
279 // The photon is assumed to be created a the end of the radiator. The
280 // distance after which it deposits its energy takes into account the
281 // absorbtion of the entrance window and of the gas mixture in drift
286 const Int_t kPdgElectron = 11;
289 const Float_t kWion = 23.53;
291 // Maximum number of TR photons per track
292 const Int_t kNTR = 50;
297 // Create TR at the entrance of the chamber
298 if (gMC->IsTrackEntering()) {
300 // Create TR only for electrons
301 Int_t iPdg = gMC->TrackPid();
302 if (TMath::Abs(iPdg) != kPdgElectron) {
310 gMC->TrackMomentum(mom);
311 Float_t pTot = mom.Rho();
312 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
314 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
317 // Loop through the TR photons
318 for (Int_t iTR = 0; iTR < nTR; iTR++) {
320 Float_t energyMeV = eTR[iTR] * 0.001;
321 Float_t energyeV = eTR[iTR] * 1000.0;
322 Float_t absLength = 0.0;
325 // Take the absorbtion in the entrance window into account
326 Double_t muMy = fTR->GetMuMy(energyMeV);
327 sigma = muMy * fFoilDensity;
329 absLength = gRandom->Exp(1.0/sigma);
330 if (absLength < AliTRDgeometry::MyThick()) {
338 // The absorbtion cross sections in the drift gas
339 // Gas-mixture (Xe/CO2)
340 Double_t muXe = fTR->GetMuXe(energyMeV);
341 Double_t muCO = fTR->GetMuCO(energyMeV);
342 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
344 // The distance after which the energy of the TR photon
347 absLength = gRandom->Exp(1.0/sigma);
348 if (absLength > (AliTRDgeometry::DrThick()
349 + AliTRDgeometry::AmThick())) {
357 // The position of the absorbtion
359 gMC->TrackPosition(pos);
360 posHit[0] = pos[0] + mom[0] / pTot * absLength;
361 posHit[1] = pos[1] + mom[1] / pTot * absLength;
362 posHit[2] = pos[2] + mom[2] / pTot * absLength;
365 Int_t q = ((Int_t) (energyeV / kWion));
367 // Add the hit to the array. TR photon hits are marked
368 // by negative charge
369 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
381 //_____________________________________________________________________________
382 void AliTRDv1::Init()
385 // Initialise Transition Radiation Detector after geometry has been built.
390 AliDebug(1,"Slow simulator\n");
392 // Switch on TR simulation as default
394 AliInfo("TR simulation off");
397 fTR = new AliTRDsim();
400 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
401 const Float_t kPoti = 12.1;
402 // Maximum energy (50 keV);
403 const Float_t kEend = 50000.0;
404 // Ermilova distribution for the delta-ray spectrum
405 Float_t poti = TMath::Log(kPoti);
406 Float_t eEnd = TMath::Log(kEend);
408 // Ermilova distribution for the delta-ray spectrum
409 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
411 // Geant3 distribution for the delta-ray spectrum
412 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
414 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
418 //_____________________________________________________________________________
419 void AliTRDv1::StepManager()
422 // Slow simulator. Every charged track produces electron cluster as hits
423 // along its path across the drift volume.
426 switch (fTypeOfStepManager) {
428 StepManagerErmilova();
434 StepManagerFixedStep();
437 AliWarning("Not a valid Step Manager.");
442 //_____________________________________________________________________________
443 void AliTRDv1::SelectStepManager(Int_t t)
446 // Selects a step manager type:
449 // 2 - Fixed step size
452 fTypeOfStepManager = t;
453 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
457 //_____________________________________________________________________________
458 void AliTRDv1::StepManagerGeant()
461 // Slow simulator. Every charged track produces electron cluster as hits
462 // along its path across the drift volume. The step size is set acording
463 // to Bethe-Bloch. The energy distribution of the delta electrons follows
464 // a spectrum taken from Geant3.
466 // Version by A. Bercuci
484 Double_t stepSize = 0;
486 Bool_t drRegion = kFALSE;
487 Bool_t amRegion = kFALSE;
490 TString cIdSensDr = "J";
491 TString cIdSensAm = "K";
492 Char_t cIdChamber[3];
500 const Int_t kNplan = AliTRDgeometry::Nplan();
501 const Int_t kNcham = AliTRDgeometry::Ncham();
502 const Int_t kNdetsec = kNplan * kNcham;
504 const Double_t kBig = 1.0e+12; // Infinitely big
505 const Float_t kWion = 23.53; // Ionization energy
506 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
508 // Minimum energy for the step size adjustment
509 const Float_t kEkinMinStep = 1.0e-5;
510 // energy threshold for production of delta electrons
511 const Float_t kECut = 1.0e4;
512 // Parameters entering the parametrized range for delta electrons
513 const Float_t kRa = 5.37e-4;
514 const Float_t kRb = 0.9815;
515 const Float_t kRc = 3.123e-3;
516 // Gas density -> To be made user adjustable !
517 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
518 const Float_t kRho = 0.004945 ;
520 // Plateau value of the energy-loss for electron in xenon
521 // The averaged value (26/3/99)
522 const Float_t kPlateau = 1.55;
523 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
524 const Float_t kPrim = 19.34;
525 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
526 const Float_t kPoti = 12.1;
528 const Int_t kPdgElectron = 11;
530 // Set the maximum step size to a very large number for all
531 // neutral particles and those outside the driftvolume
532 gMC->SetMaxStep(kBig);
534 // Use only charged tracks
535 if (( gMC->TrackCharge() ) &&
536 (!gMC->IsTrackDisappeared())) {
538 // Inside a sensitive volume?
541 cIdCurrent = gMC->CurrentVolName();
542 if (cIdSensDr == cIdCurrent[1]) {
545 if (cIdSensAm == cIdCurrent[1]) {
548 if (drRegion || amRegion) {
550 // The hit coordinates and charge
551 gMC->TrackPosition(pos);
556 // The sector number (0 - 17)
557 // The numbering goes clockwise and starts at y = 0
558 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
565 sec = ((Int_t) (phi / 20.0));
567 // The plane and chamber number
568 cIdChamber[0] = cIdCurrent[2];
569 cIdChamber[1] = cIdCurrent[3];
570 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
571 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
572 pla = ((Int_t) idChamber % kNplan);
574 // Check on selected volumes
575 Int_t addthishit = 1;
580 // The detector number
581 det = fGeometry->GetDetector(pla,cha,sec);
583 // Special hits only in the drift region
586 // Create a track reference at the entrance and
587 // exit of each chamber that contain the
588 // momentum components of the particle
589 if (gMC->IsTrackEntering() ||
590 gMC->IsTrackExiting()) {
591 gMC->TrackMomentum(mom);
592 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
595 if (gMC->IsTrackEntering() &&
596 !gMC->IsNewTrack()) {
597 // determine if hit belong to primary track
598 fPrimaryTrackPid = gAlice->GetMCApp()->GetCurrentTrackNumber();
599 // determine track length when entering the detector
600 fTrackLength0 = gMC->TrackLength();
603 // Create the hits from TR photons
604 if (fTR) CreateTRhit(det);
608 // Calculate the energy of the delta-electrons
609 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
610 // take into account correlation with the underlying GEANT tracking
612 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
614 // determine the most significant process (last on the processes list)
615 // which caused this hit
616 gMC->StepProcesses(processes);
617 Int_t nofprocesses = processes.GetSize();
623 pid = processes[nofprocesses-1];
626 // generate Edep according to GEANT parametrisation
627 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
628 eDelta = TMath::Max(eDelta,0.0);
629 Float_t prRange = 0.0;
630 Float_t range = gMC->TrackLength() - fTrackLength0;
631 // merge GEANT tracker information with locally cooked one
632 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
634 if (eDelta >= kECut) {
635 prRange = kRa * eDelta * 0.001
636 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
637 if (prRange >= (3.7 - range)) {
643 if (eDelta < kECut) {
647 prRange = kRa * eDelta * 0.001
648 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
649 if (prRange >= ((AliTRDgeometry::DrThick()
650 + AliTRDgeometry::AmThick()) - range)) {
666 // Generate the electron cluster size
671 qTot = ((Int_t) (eDelta / kWion) + 1);
674 // Create a new dEdx hit
675 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
681 // Calculate the maximum step size for the next tracking step
682 // Produce only one hit if Ekin is below cutoff
683 aMass = gMC->TrackMass();
684 if ((gMC->Etot() - aMass) > kEkinMinStep) {
686 // The energy loss according to Bethe Bloch
687 iPdg = TMath::Abs(gMC->TrackPid());
688 if ((iPdg != kPdgElectron) ||
689 ((iPdg == kPdgElectron) &&
690 (pTot < kPTotMaxEl))) {
691 gMC->TrackMomentum(mom);
693 betaGamma = pTot / aMass;
694 pp = BetheBlochGeant(betaGamma);
695 // Take charge > 1 into account
696 charge = gMC->TrackCharge();
697 if (TMath::Abs(charge) > 1) {
698 pp = pp * charge*charge;
702 // Electrons above 20 Mev/c are at the plateau
703 pp = kPrim * kPlateau;
708 nsteps = gRandom->Poisson(pp);
710 stepSize = 1.0 / nsteps;
711 gMC->SetMaxStep(stepSize);
723 //_____________________________________________________________________________
724 void AliTRDv1::StepManagerErmilova()
727 // Slow simulator. Every charged track produces electron cluster as hits
728 // along its path across the drift volume. The step size is set acording
729 // to Bethe-Bloch. The energy distribution of the delta electrons follows
730 // a spectrum taken from Ermilova et al.
751 Bool_t drRegion = kFALSE;
752 Bool_t amRegion = kFALSE;
755 TString cIdSensDr = "J";
756 TString cIdSensAm = "K";
757 Char_t cIdChamber[3];
763 const Int_t kNplan = AliTRDgeometry::Nplan();
764 const Int_t kNcham = AliTRDgeometry::Ncham();
765 const Int_t kNdetsec = kNplan * kNcham;
767 const Double_t kBig = 1.0e+12; // Infinitely big
768 const Float_t kWion = 23.53; // Ionization energy
769 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
771 // Minimum energy for the step size adjustment
772 const Float_t kEkinMinStep = 1.0e-5;
774 // Plateau value of the energy-loss for electron in xenon
775 // The averaged value (26/3/99)
776 const Float_t kPlateau = 1.55;
777 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
778 const Float_t kPrim = 48.0;
779 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
780 const Float_t kPoti = 12.1;
782 const Int_t kPdgElectron = 11;
784 // Set the maximum step size to a very large number for all
785 // neutral particles and those outside the driftvolume
786 gMC->SetMaxStep(kBig);
788 // Use only charged tracks
789 if (( gMC->TrackCharge() ) &&
790 (!gMC->IsTrackDisappeared())) {
792 // Inside a sensitive volume?
795 cIdCurrent = gMC->CurrentVolName();
796 if (cIdSensDr == cIdCurrent[1]) {
799 if (cIdSensAm == cIdCurrent[1]) {
802 if (drRegion || amRegion) {
804 // The hit coordinates and charge
805 gMC->TrackPosition(pos);
810 // The sector number (0 - 17)
811 // The numbering goes clockwise and starts at y = 0
812 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
819 sec = ((Int_t) (phi / 20.0));
821 // The plane and chamber number
822 cIdChamber[0] = cIdCurrent[2];
823 cIdChamber[1] = cIdCurrent[3];
824 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
825 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
826 pla = ((Int_t) idChamber % kNplan);
828 // Check on selected volumes
829 Int_t addthishit = 1;
834 // The detector number
835 det = fGeometry->GetDetector(pla,cha,sec);
837 // Special hits only in the drift region
840 // Create a track reference at the entrance and
841 // exit of each chamber that contain the
842 // momentum components of the particle
843 if (gMC->IsTrackEntering() ||
844 gMC->IsTrackExiting()) {
845 gMC->TrackMomentum(mom);
846 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
848 // Create the hits from TR photons
855 // Calculate the energy of the delta-electrons
856 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
857 eDelta = TMath::Max(eDelta,0.0);
858 // Generate the electron cluster size
863 qTot = ((Int_t) (eDelta / kWion) + 1);
866 // Create a new dEdx hit
868 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
875 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
882 // Calculate the maximum step size for the next tracking step
883 // Produce only one hit if Ekin is below cutoff
884 aMass = gMC->TrackMass();
885 if ((gMC->Etot() - aMass) > kEkinMinStep) {
887 // The energy loss according to Bethe Bloch
888 iPdg = TMath::Abs(gMC->TrackPid());
889 if ((iPdg != kPdgElectron) ||
890 ((iPdg == kPdgElectron) &&
891 (pTot < kPTotMaxEl))) {
892 gMC->TrackMomentum(mom);
894 betaGamma = pTot / aMass;
895 pp = kPrim * BetheBloch(betaGamma);
896 // Take charge > 1 into account
897 charge = gMC->TrackCharge();
898 if (TMath::Abs(charge) > 1) {
899 pp = pp * charge*charge;
903 // Electrons above 20 Mev/c are at the plateau
904 pp = kPrim * kPlateau;
909 gMC->GetRandom()->RndmArray(1,random);
911 while ((random[0] == 1.0) ||
913 stepSize = - TMath::Log(random[0]) / pp;
914 gMC->SetMaxStep(stepSize);
927 //_____________________________________________________________________________
928 void AliTRDv1::StepManagerFixedStep()
931 // Slow simulator. Every charged track produces electron cluster as hits
932 // along its path across the drift volume. The step size is fixed in
933 // this version of the step manager.
945 Bool_t drRegion = kFALSE;
946 Bool_t amRegion = kFALSE;
949 TString cIdSensDr = "J";
950 TString cIdSensAm = "K";
951 Char_t cIdChamber[3];
957 const Int_t kNplan = AliTRDgeometry::Nplan();
958 const Int_t kNcham = AliTRDgeometry::Ncham();
959 const Int_t kNdetsec = kNplan * kNcham;
961 const Double_t kBig = 1.0e+12;
963 const Float_t kWion = 23.53; // Ionization energy
964 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
966 // Set the maximum step size to a very large number for all
967 // neutral particles and those outside the driftvolume
968 gMC->SetMaxStep(kBig);
970 // If not charged track or already stopped or disappeared, just return.
971 if ((!gMC->TrackCharge()) ||
972 gMC->IsTrackDisappeared()) return;
974 // Inside a sensitive volume?
975 cIdCurrent = gMC->CurrentVolName();
977 if (cIdSensDr == cIdCurrent[1]) drRegion = kTRUE;
978 if (cIdSensAm == cIdCurrent[1]) amRegion = kTRUE;
985 // The hit coordinates and charge
986 gMC->TrackPosition(pos);
991 // The sector number (0 - 17)
992 // The numbering goes clockwise and starts at y = 0
993 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
1000 sec = ((Int_t) (phi / 20.0));
1002 // The plane and chamber number
1003 cIdChamber[0] = cIdCurrent[2];
1004 cIdChamber[1] = cIdCurrent[3];
1005 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
1006 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
1007 pla = ((Int_t) idChamber % kNplan);
1009 // Check on selected volumes
1010 Int_t addthishit = 1;
1016 // The detector number
1017 det = fGeometry->GetDetector(pla,cha,sec);
1019 // 0: InFlight 1:Entering 2:Exiting
1022 // Special hits only in the drift region
1025 // Create a track reference at the entrance and exit of each
1026 // chamber that contain the momentum components of the particle
1028 if (gMC->IsTrackEntering()) {
1029 gMC->TrackMomentum(mom);
1030 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
1033 if (gMC->IsTrackExiting()) {
1034 gMC->TrackMomentum(mom);
1035 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
1039 // Create the hits from TR photons
1046 // Calculate the charge according to GEANT Edep
1047 // Create a new dEdx hit
1048 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1049 qTot = (Int_t) (eDep / kWion);
1050 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1056 // Set Maximum Step Size
1057 // Produce only one hit if Ekin is below cutoff
1058 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1061 gMC->SetMaxStep(fStepSize);
1065 //_____________________________________________________________________________
1066 Double_t AliTRDv1::BetheBloch(Double_t bg)
1069 // Parametrization of the Bethe-Bloch-curve
1070 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1073 // This parameters have been adjusted to averaged values from GEANT
1074 const Double_t kP1 = 7.17960e-02;
1075 const Double_t kP2 = 8.54196;
1076 const Double_t kP3 = 1.38065e-06;
1077 const Double_t kP4 = 5.30972;
1078 const Double_t kP5 = 2.83798;
1080 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1081 const Double_t kBgMin = 0.8;
1082 const Double_t kBBMax = 6.83298;
1085 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1086 Double_t aa = TMath::Power(yy,kP4);
1087 Double_t bb = TMath::Power((1.0/bg),kP5);
1088 bb = TMath::Log(kP3 + bb);
1089 return ((kP2 - aa - bb) * kP1 / aa);
1097 //_____________________________________________________________________________
1098 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1101 // Return dN/dx (number of primary collisions per centimeter)
1102 // for given beta*gamma factor.
1104 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1105 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1106 // This must be used as a set with IntSpecGeant.
1111 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1112 , 1.800000, 2.000000, 2.500000, 3.000000
1113 , 4.000000, 7.000000, 10.000000, 20.000000
1114 , 40.000000, 70.000000, 100.000000, 300.000000
1115 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1117 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1118 , 22.734999, 21.411915, 19.934095, 19.449375
1119 , 19.344431, 20.185553, 21.027925, 22.912676
1120 , 24.933352, 26.504053, 27.387468, 29.566597
1121 , 30.353779, 30.787134, 31.129285, 31.157350 };
1123 // Betagamma to gamma
1124 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1126 // Find the index just before the point we need.
1127 for (i = 0; i < 18; i++) {
1128 if ((arrG[i] < g) &&
1134 // Simple interpolation.
1135 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1136 * (g - arrG[i]) + arrNC[i];
1142 //_____________________________________________________________________________
1143 Double_t Ermilova(Double_t *x, Double_t *)
1146 // Calculates the delta-ray energy distribution according to Ermilova.
1147 // Logarithmic scale !
1157 const Int_t kNv = 31;
1159 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1160 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1161 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1162 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1163 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1164 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1167 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1168 , 20.9, 20.8, 20.0, 16.0, 11.0
1169 , 8.0, 6.0, 5.2, 4.6, 4.0
1170 , 3.5, 3.0, 1.4, 0.67, 0.44
1171 , 0.3, 0.18, 0.12, 0.08, 0.056
1172 , 0.04, 0.023, 0.015, 0.011, 0.01
1177 // Find the position
1182 dpos = energy - vxe[pos2++];
1191 // Differentiate between the sampling points
1192 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1198 //_____________________________________________________________________________
1199 Double_t IntSpecGeant(Double_t *x, Double_t *)
1202 // Integrated spectrum from Geant3
1205 const Int_t npts = 83;
1206 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1207 , 2.672067, 2.813299, 3.015059, 3.216819
1208 , 3.418579, 3.620338, 3.868209, 3.920198
1209 , 3.978284, 4.063923, 4.186264, 4.308605
1210 , 4.430946, 4.553288, 4.724261, 4.837736
1211 , 4.999842, 5.161949, 5.324056, 5.486163
1212 , 5.679688, 5.752998, 5.857728, 5.962457
1213 , 6.067185, 6.171914, 6.315653, 6.393674
1214 , 6.471694, 6.539689, 6.597658, 6.655627
1215 , 6.710957, 6.763648, 6.816338, 6.876198
1216 , 6.943227, 7.010257, 7.106285, 7.252151
1217 , 7.460531, 7.668911, 7.877290, 8.085670
1218 , 8.302979, 8.353585, 8.413120, 8.483500
1219 , 8.541030, 8.592857, 8.668865, 8.820485
1220 , 9.037086, 9.253686, 9.470286, 9.686887
1221 , 9.930838, 9.994655, 10.085822, 10.176990
1222 , 10.268158, 10.359325, 10.503614, 10.627565
1223 , 10.804637, 10.981709, 11.158781, 11.335854
1224 , 11.593397, 11.781165, 12.049404, 12.317644
1225 , 12.585884, 12.854123, 14.278421, 16.975889
1226 , 20.829416, 24.682943, 28.536469 };
1228 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1229 , 9.1601500, 8.206670, 6.919630, 5.655430
1230 , 4.6221300, 3.777610, 3.019560, 2.591950
1231 , 2.5414600, 2.712920, 3.327460, 4.928240
1232 , 7.6185300, 10.966700, 12.225800, 8.094750
1233 , 3.3586900, 1.553650, 1.209600, 1.263840
1234 , 1.3241100, 1.312140, 1.255130, 1.165770
1235 , 1.0594500, 0.945450, 0.813231, 0.699837
1236 , 0.6235580, 2.260990, 2.968350, 2.240320
1237 , 1.7988300, 1.553300, 1.432070, 1.535520
1238 , 1.4429900, 1.247990, 1.050750, 0.829549
1239 , 0.5900280, 0.395897, 0.268741, 0.185320
1240 , 0.1292120, 0.103545, 0.0949525, 0.101535
1241 , 0.1276380, 0.134216, 0.123816, 0.104557
1242 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1243 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1244 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1245 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1246 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1247 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1248 , 3.63304e-06, 0.0000000, 0.0000000 };
1251 Double_t energy = x[0];
1253 for (i = 0; i < npts; i++) {
1254 if (energy < arre[i]) {
1260 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");